Fix: wait for device to close

core/device/device.go

@@ -17,4 +17,7 @@ type Device interface {
 
 	// Type returns the driver type of the device.
 	Type() string
+
+	// Wait waits for the device to close.
+	Wait()
 }

core/device/tun/tun_wireguard.go

@@ -79,5 +79,6 @@ func (t *TUN) Name() string {
 }
 
 func (t *TUN) Close() error {
+	t.Endpoint.Close()
 	return t.nt.Close()
 }

engine/engine.go

@@ -80,13 +80,16 @@ func (e *engine) start() error {
 	return nil
 }
 
-func (e *engine) stop() error {
+func (e *engine) stop() (err error) {
 	if e.device != nil {
-		return e.device.Close()
+		err = e.device.Close()
+		e.device.Wait()
 	}
+	if e.stack != nil {
 		e.stack.Close()
 		e.stack.Wait()
-	return nil
+	}
+	return err
 }
 
 func (e *engine) insert(k *Key) {